I have installed Cygwin, but I didn't see Clang or LLVM in the list of Cygwin installation packages when choosing devel, GCC, GDB etc.
How do I install Clang on Cygwin? I want to use it for compiling C++.
CLang is available from setup:
be sure to be connected to internet and not using local cache.
Use the Full view. You can use the search to reduce the number of packages
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Is there a way to get clang/clang++ to use a gcc/g++ installation in a non-standard (i.e. not /usr) place?
I'm trying to get AMD's AOCC 4.0 compiler to work. They provide a pre-compiled version that you just unpack. The problem is that it seems to assume gcc is in /usr/lib/gcc/... In my case I'm on CentOS 7 so that's gcc 4.8.5. I want to use newer gcc's install in /sw/opt (and managed with environment modules) but even if the gcc is in my path, clang only finds that 4.8.5 version in /usr. This is also a problem in that I have a cluster that has no default gcc installed (but many gcc versions installed in /cluster/sw) and I can't get clang to see them.
When I want LLVM I usually just build from scratch and specify GCC_INSTALL_PREFIX but that only seems to be useful at build time and since AMD only provides executables I'm out of luck.
Ideally I'd like to get clang/clang++ to point to another gcc (en mass: include, libs, etc...) or not be dependent on gcc at all.
AOCC seems to be based on 14.0.6 if that matters:
AMD clang version 14.0.6 (CLANG: AOCC_4.0.0-Build#434 2022_10_28) (based on LLVM Mirror.Version.14.0.6)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /sw/opt/aocc-compiler-4.0.0/bin
After more poking around I've discovered that there is a clang option "--gcc-toolchain" that seems to address this. Some clang documentation also lists an option "--gcc-install-dir" but neither the 14.0.6 based version of AOCC nor the 16.0.0 based version of OneAPI (2023.0) seem to recognize it. I don't see it in the output of "clang --help" either so who knows.
Successfully installed opencv 4.5.4 in windows under mingw evironment. I was able to compile opencv applications. But is there any easy way to give reference to libraries instead of typing long list of opencv libraries (i.e. something like pkg-config in windows)
For a simple opencv program I need to give reference to 4 libraries.
g++ rotate.cpp -lopencv_core454 -lopencv_highgui454 -lopencv_imgproc454 -lopencv_imgcodecs454
instead do we have some option to give list of libraries through some flags in windows environment.
Thanks
You can actually use pkg-config in Windows. If you use MSYS2 shell is is usually available or it can be installed via pacman.
What I'm trying to achieve is to compile an GNU independent and isolated LLVM toolchain using musl as clib.
Recently LLVM 4.0 has been released with lot's of new cool features, including production ready LLD, so also the linking step could be handled by LLVM.
More or less the stack is:
clang
llvm
lld
compiler-rt
libcxx
libcxxabi
musl
Following this, it is actually possible to do so without much patching or such (apart from compiling musl), but sadly, there is no good documentation about that.
Any suggestions?
There is an example of using Clang + Musl together to compile "Hello World" in C here: https://github.com/njlr/portable-cxx
It only requires wget, tar and make to be installed. Clang and Musl are downloaded as part of the build process.
The key is to disable the usual include paths using -nostdinc and then add the Musl ones using -isystem.
I was solving the same problem with my NGTC (Non-GNU toolchain) project. Please take a look at my build scripts and patches.
I used this toolchain to build a small Linux distro without any code from GNU project: nenuzhnix.
I ran clang++ -v testfile.cpp and found that many standard headers were missing from the directory C:\LLVM\lib\clang\3.9.0\include. I downloaded a pre-built binary of clang 3.9.0 for 32 bit windows from this link.
Can someone please help me sort out this mess and explain me why the standard libraries are missing in the pre-build version of clang? I've searched the web for hours to get the answer and solution to this problem but couldn't find one. Thanks in advance.
why the standard libraries are missing in the pre-build version of clang?
Your Windows binary download comprises only binary build tools
plus a handful of clang-specific headers because you are supposed
to use clang, on Windows, in lieu of another native compiler that provides your
standard library. Similarly if you install clang on Linux you'll build against
the GCC standard library by default.
Your internet search seemingly failed to lead you to Installing clang++ to compile and link on Windows, which
explains how to integrate clang with the mingw-w64 GCC standard library for 32- and/or 64-bit work
in the manner that clang for Windows expects and supports.
I am trying to build Clang following this: http://clang.llvm.org/get_started.html
At step 6 the command ../llvm/configure runs a series of checks and one tells me:
checking whether Clang will select a modern C++ standard library... no
configure: error:
We detected a missing feature in the standard C++ library that was known to be
missing in libstdc++4.6 and implemented in libstdc++4.7. There are numerous
C++11 problems with 4.6's library, and we don't support GCCs or libstdc++ older
than 4.7. You will need to update your system and ensure Clang uses the newer
standard library.
If this error is incorrect or you need to force things to work, you may pass
'--disable-compiler-version-checks' to configure to bypass this test.
I don't know how to resolve this and google searches for libstdc++4.7 did not produce anything useful to me or something I understand. How do I go about replacing / upgrading this? I am on a Mac (10.7.5)
I ran into the same problem. The easiest way to build Clang is to use libc++ instead of libstdc++. If you don't have libc++, you can obtain it by installing XCode 4.2 (or newer) or you can build it yourself by following the instructions here: http://libcxx.llvm.org/
After you have libc++ installed, you can use the --enable-libcpp=yes flag with the configure command.
Just this week, the LLVM & Clang project upped the minimal compiler version requirement to gcc 4.7, with its libstdc++. You'll need to install or build a newer gcc.
Here's a blog post I wrote earlier today about building gcc 4.8 on Ubuntu 12.04 and using that to compile trunk LLVM & Clang. Hope this helps!
i have the same error on mac 10.8.5 xcode 5.0
configure option --enable-libcpp resolve my problem
../llvm/configure --enable-cxx11 --enable-optimized --enable-libcpp
For me this happened because I had the old clang and clang++ that I'd previously built from source (the one I was attempting to build to replace) coming first in my PATH. These were too old. Removing those two files so that the build process would use the clang and clang++ that comes with XCode's Command Line Tools and then rebuilding worked fine.